This invention relates generally to the construction of retaining walls used in landscaping applications. Such walls are used to provide lateral support between differing ground levels where the change in one elevation to the other occurs over a relatively short distance, thereby reducing the possibility of erosion and landslides. Retaining walls can be both functional and decorative and range from small gardening applications to large-scale construction. They are constructed of a variety of materials and shapes. Some have been constructed of wood timbers, others of rock in a natural form (such as limestone). Still others have been constructed of manufactured aggregate or concrete blocks. The present invention relates to a manufactured block.
Constructing a fit and true retaining wall can be an arduous endeavor. In addition to laying a level first course on ground which is usually located at the foot or in the side of a steep embankment, the builder must ensure that each subsequent course is level. An error made in a lower course usually gets exaggerated as higher courses are stacked above it. As a wall made of blocks necessarily develops somewhat of a grid-like appearance, interruptions or undulations in the lines of the wall become readily apparent to the human eye.
One particular problem the prior art has failed to overcome is developing a retaining wall block shaped to avoid these undulations and interruptions which are caused by blocks being stacked on dirt or debris found on the upper surface of the lower course of blocks. Dirt presents itself as a result of the fill material used to fill the gap between the rear of the wall and the earth it is being built to retain. This fill material usually consists of small, coarse rocks. They serve as a barrier between the earth and the wall and prevent wet earth from seeping through the bricks of the wall during inclement weather. Present wall building methods include laying a course of blocks, filling the space behind the course with fill material, packing the fill material, and carefully sweeping the dirt off of each completed course prior to the addition of the next course. This final, sweeping step is time consuming but necessary to ensure the next course of blocks lies flat on the lower course.
Some larger blocks incorporate continuous cavities that extend from their bottom surface to their top surfaces. These cavities are intended to reduce the amount of material required to form the block, thereby reducing its cost and weight, and also allow an area to be filled with fill material once a course is finished. At first blush it would appear that, because the presence of cavities reduces the surface area of the top and bottom of the block, they would also serve to decrease the area for interference by small stones and debris between courses. However, because the cavities are filled with fill material, the fill material spills over the upper surfaces and exacerbates, rather than alleviates, the problem. Furthermore, smaller blocks cannot incorporate cavity portions without jeopardizing their structural integrity.
The inability of smaller blocks to accommodate cavity portions creates further problems. Making a solid block out of concrete results in a dense rock which is heavy for its relatively small size. Working with these rocks can become cumbersome. The absence of cavities or interruption in the side walls makes these blocks difficult to lift. They have few areas which lend themselves to easy gripping and lifting. This becomes an important consideration in light of the number of blocks that must be lifted and set in place during the construction of even a relatively small retaining wall.
It would be desirable to develop a retaining wall block shaped to accept a certain amount of dirt and debris from course to course without adversely affecting the overall structure and aesthetics of the resulting wall. It would also be desirable to devise a small retaining wall block which is has a reduced unit weight due to the absence of block material in an area that will not adversely affect the strength of the block, nor its appearance. Finally, it would be desirable to provide a small retaining wall block which is relatively easy to grasp and pick up off of a stack of similar blocks.
The present invention advantageously provides a block for use in building a retaining wall that produces a level course of blocks, despite the presence of a small amount of debris on the lower course of blocks.
The present invention is also advantageous in that it provides a relatively small block with material removed from strategic locations to provide a block which is lighter than it would have been had it been solid, yet the removal of material has not adversely affected the strength of the block, nor the appearance of the resulting wall.
The present invention advantageously provides a block which has areas for a person building a retaining wall to grasp the block when lifting the block off of a stack of such blocks and placing the block on a lower course of blocks in the wall being constructed.
The instant invention relates to a retaining wall block so shaped that when placed on top of a lower course of similar blocks, it lies flat despite the inevitable presence of dirt, small stones, and other debris. This feature alleviates the time-consuming step of meticulously cleaning the top of each course of blocks before the next course may be laid on top of it.
The block generally comprises a continuous top surface, side surfaces extending from the top surface, front and back surfaces extending from the top surface and spanning laterally between the side surfaces and a bottom surface integral with the front, back and side surfaces.
In order to achieve the tolerance of small stones and debris between courses, a portion of the bottom face of the block of the present invention is non-planar, more specifically, concave. This concave surface significantly reduces the area for block to block contact between successive courses. Preferably, this non-planar portion covers more than one half of the area of the bottom surface of the block. It also functions to provide an area of clearance or a gap between the stones where debris can migrate without causing interference or instability between courses. The concave portion is preferably shaped to form a portion of a cylinder and extends from one side surface to the other. Alternatively, the concave portion could be shaped to form a portion of a sphere or any other shape.
In addition to the concave portion of the bottom surface, the present invention further comprises a plurality of grooves formed in the bottom surface and preferably extending transversely of the bottom surface between the front and back surfaces. The grooves preferably are angled inwardly to form an inverted xe2x80x9cVxe2x80x9d shape when the block is given its intended orientation. The grooves allow spaces of increased clearance for larger stones. The grooves preferably comprise two opposed surfaces of a predetermined width extending the length of the groove. The two surfaces are angled to form a xe2x80x9cVxe2x80x9d shape and meet to form an angle xcex1. The angled walls of the grooves not only reduce the weight of the block, but also act to funnel larger stones into the grooves, thereby positioning them into an area of maximum clearance. Alternatively, the first and second surfaces may be joined by a third, curved or flat, surface juxtaposed between the first and second surfaces. Such a third surface would give the groove an inverted xe2x80x9cUxe2x80x9d shape. The grooves are cut into the block and have a set depth which follows the irregular contour of the non-planar bottom surface.
Preferably, the bottom surface further comprises one or more downward projections proximate the rear surface and having an abutting surface which contacts the rear surface of a lower course of blocks when the block is stacked thereon. It is envisioned that the abutting surface is either parallel to the rear surface of the block, or forms an angle xcex2 with the rear surface. These projections create an automatic and uniform setback among successive courses of blocks so that the resulting retaining wall is angled rearwardly. This adds resistive strength to the wall against the natural forces exerted on the wall by the earth the wall is retaining.